Dryer felt



May 10, 1966 E. D. BEACHLER DRYER FELT Filed Sept. 10, 1962 QM a Q m w s A @N QwN N b N a YN m, C wwN w 2 w e N A Edward 0. 5 22 2???- BY 1 v' v ATTOI NEYS United States Patent 0 3,250,019 DRYER FELT Edward D. Beachler, Terrace Lane, Beloit, Wis. Filed Sept. 10, 1962, Ser. No. 222,309 6 Claims. (Cl. 34-117) The present invention relates to improvements in dryer sections of paper machines and more particularly to an improved felt arrangement for paper machine dryer parts.

In the usual paper machine dryer part, there are provided a plurality of tiers of paper dryers. Ordinarily only one upper tier and one lower tier are provided for the paper Web, with a plurality of parallel aligned paper dryers in each tier. The dryers each provide a shell which is heated internally with steam and which is rotatable. The paper travels a serpentine path through the dryer parts passing beneath a first dryer in the lower tier, then over a first dryer in the upper tier, and then back down beneath the second dryer in the lower tier, etc.

Travelling looped felts pass over the tops of each of the dryers in the upper tier so as to engage the paper web during most of its travel on such dryers to hold the web in good thermal contact and minimize shrinkage and cockle. There are also provided travelling looped felts trained over the bottom of the dryers in the lower tier so as to cover the paper web during most of its travel on the dryers of the lower tier. More than one upper felt and more than one lower felt are required in each case. A first upper felt will cover the tops of a first plurality of dryers in the upper tier and then be directed away from the upper tier of dryers; and a second upper felt will cover a second plurality of dryers in this tier immediately adjacent to the first plurality. Plural lower felts are similarly handled. When starting or restoring a web to the machine it has been necessary to thread a narrow tail by hand or by Sheehan ropes. The relatively sudden thermal load change when a web breaks or when the tail is followed by a full width sheet causes considerable difficulty in controlling the steam supply or other heat energy to the dryers.

It is an object of the invention to provide'an arrangement wherein improved drying is achieved and improved paper web contact with the dryers occurs.

It is anobject of the present invention to provide a means for supporting the heretofore unsupported span between top and bottom tiers of dryers in order to avoid the disadvantages .accompanying lack of support.

' 'A further object of the invention is to provide a means for avoiding flapping of the sheet, i.e. a non-steady state of travel, which now occurs in the unsupported span between top'and bottom dryers, and particularly in the relatively long span at the felt breaks, such as caused by non-uniformity of the web and non-uniformity of the air flow.

Another object is to provide an arrangement where the felt means wraps the same zone of contact with the dryer as the web and therefore effectively holds the web against the dryer throughout this contact zone.

An object of the invention is to provide an arrangement that has complete control of the web path through a dryer part, usually including several sections, and Where a continuously defined path is available for taking the web through the dryer part which continuesto carry even a torn end over the dryers.

A further object of the invention is to provide a mechanism whichaffords more uniform drying across the machine in a dryer section.

Yet another object of the invention is to provide a mechanism which avoids frequent sheet breaks in a dryer section of a paper machine.

A still further object of the invention is to provide a mechanism which provides a novel means of sheet threading which can be used to greatly assist conventional threading operation, and which can be used for threading the entire width of the web under certain conditions.

Another object of the invention is to avoid the adverse effects caused by the break between felts of the lower tier of dryers. I

A feature of the invention is the rearrangement of the carrying felts in a dryer section of the machine so that the bottom felt and the top felt are guided down in between the dryers to support the web in its path between the upper and lower tiers of dryers. The top felt is brought down to a position, and the bottom felt is brought up to a position so that the felts overlap to provide continuous support for the paper web, and the spaces between the bottom dryers and top felt, and between the upper dryers and bottom felt are pressurized by means of air supply ducts which force air through the carrying felts and which pressurize pockets between the felts and dryers to hold the web against the carrying felts. The carrying felts are directed over the dryers for the same are of contact as the web so that the web is forced against the dryer for its full arc of engagement.

Other objects, advantages and features will become more apparent with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiment thereof in the specification, claims and drawing, in which:

The single figure of the drawing is a schematic front elevational view of the end of the portion of a dryer section of a machine constructed and operating in accordance with the principles of the present invention. 1

As shown on the drawing:

The travelling paper web w is shown moving from left to right in the drawing, entering the dryer section as it leaves the-nip of a press section formed between the press rolls 8 and 9, the nip also receiving a press felt 7. The web follows a suction type pickup roll 12 having a suction gland 13. The pickup roll 12 is wrapped by a lower felt I F which carries the web to the dryers.

The dryers include a lower or second tier of dryers 14, 15, and an end dryer 16 which will later be referred to as a single dryer in that it carries the Web between a first plurality of dryers of the lower tier T to a second plurality. The first plurality of lower dryers is served by, the felt F and another felt F will be-used for the second plurality. v i

An upper or first tier of dryers includes dryers -17 and 18, and this tier is served by a first felt F The upper tier includes a second plurality which is served by another upper felt F' The second lower tier is served by the second felt F' which begins at the single dryer 16. The felts F F F and F are felt loops supported on suitable guide rolls as will be clear to those versed in the art as being in any suitable arrangement for carrying the felt in its travelling loop, and which may be omitted from the drawing for the sake of clarity.

The felts F F F and F are formed of an open type fabric for encouraging evaporation of moisture from the web. The felts also may be formed of a plastic wire fabric such as used on Fourdriniers. A material such as a foraminous plastic wire or fabric, of the type known as Formex fabric, permits moisture vapor to be driven out of the pockets, and the fabric to be maintainedclean and open. This present arrangement will compel the web to follow the path determined by the felts.

The web is threaded in a serpentine path first passing around the first dryer 14 of the lower tier and then passing upwardly over the dryer 17 of the upper tier, subsequently being threaded downwardly around the dryer 15 and upwardly over the dryer 1-8 and then down around the single dryer 16.

While the web engages the dryers it covers an area which may be referred to as a normally web covered surface region. The dryers are of conventional construction being supplied with heat from suitable means such as a steam supply and these details of construction will be fully appreciated by those skilled in the art and need not be described in detail.

Heretofore it has been conventional to thread the upper and lower felts so that the upper felt merely engages a small portion of the arc of the upper dryers, and the lower felt merely engages a small portion of the arc of the lower dryers. Such construction is illustrated for example in my U.S. Patents 2,823,466 and 2,909,848. The web w in traversing betweenthetiers is unsupported.

In accordance with the principles of the present invention, the upper felt is provided with felt guides that bring it down to support at least one-half of each of the web runs between the upper and lower tiers. 19 brings the upper felt F down to receive the web w as it leaves the first dryer 14 of the lower tier and guide and support it as it ascends and approaches the first dryer 17 of the upper tier. The felt is brought down around the other side of the dryer 17 by a guide roll 20, and another guide roll 21 leads the felt F across to where it catches the web run as it moves up wardly from the dryer of the lower tier to the dryer 18 of the upper tier. A guide roll 22 again guides the felt F downwardly to support the web as it approaches the single dryer 16.

Similarly, the second felt P of the lower tier is brought up between the dryers, and a guide roll 23 leads the felt F up from the first dryer 14 to a position above the roll 19 for the first felt F Another guide roll 24 leads the felt F over to receive the web as it passes downwardly to the dryer 15 of the second tier..

Guide rolls 25 and 26 direct the felt F to support the web w as it moves from the dryer 15 up to the dryer 18 and back down to the dryer 16.

The guide rolls are positioned so that the rolls for the lower felt F are above the rolls for the upper felt so as to provide continuous supportfor the webs in each run.

Means are provided for supporting the web runs against the felt surface by a pressure differential.

For this purpose, an air supply duct 26a directs a flow of air against the web as it leaves the first dryer 14 ofthe lower tier and as it is supported by the felt F The duct 26a thus directs a stream of pressurized air in the direction across the web path and toward the span of felt F between dryer 14 and felt guide roll 23 in a region substantially opposite the entire felt span. Similar air streams are provided at pockets 28, 30 and 33 hereinafter referred'to. The duct 26a is positioned between the guide roll 19 and the first dryer 14, and directs air intoa pocket 26b which is formed between dryer 14 and roll 19, and between the web w and the air duct26a. Seals are provided between the sides of the duct 26a and the dryer 14 and roll 19 'to prevent the free escape of air.

The felt F as it is brought up between each pair of adjacent dryers of the lower tier, forms a pocket with the dryer above it, as illustrated by the pockets 28 and 33. Similarly, as the felt F is brought down between the dryers 17 and 18 of the upper tier toward the dryer 15 of the lower tier it forms a pocket 30. The pocket 28 is pressurized 'by an air supply duct 27 which directs air upwardly through the felt F and may be provided with seals 27a and 27b positioned between the duct 27 and the roll-s 23 and 24 to limit the air escaping past the rolls 23 and 24. The pocket 33 represents a larger space, and a pair of conduits 31 and 32 direct air up through the felt F The pocket 30 is pressurized by an air conduit 29.

A guide roll The lower felt F for the first plurality of dryers 14 and 15 of the lower tier is brought along in supporting relationship to the web as it passes onto the single dryer 16, before the felt F passes downwardly. The felt F for the second plurality of dryers of the lower tier passes in close-running parallel relationship to the first felt F This arrangement whereby the felts are running close together eliminates air currents and drafts, such as where the felts run to a cooler basement. The felt F being 'held against the Web as it approaches the dryer 16, prevents any air from passing up into any space between the Web and dryer to circulate over any substantial surface area of the web. Exposed web area engaged by cooler air such as from an extrinsic area as a basement would retard drying and promote uneven drying.

If desired, additional air jets may be provided for each area of the web where supported on one side only, such as between the dryer 16 and roll 22.

While not shown, conventional dryer doctors will usually be used to keep the dryer surfaces clean and direct the web, particularly at points where the web is likely to adhere to the dryer.

In summary, the Web w passes in a serpentine path over the dryers 17 and 18 of the upper tier and dryers 14 and 15 of the lower tier, and the span or runs of web between the tiers are positively supported by directing the felt to positions between the dryers to completely support the web, and the pockets formed are pressurized with air to hold the web against the felts. The supporting air preferably passes through the felts before entering the pockets, and thus performs a dual function of supporting the webs and accomplishing some drying of the felts. The air can also cause some drying of the Web increasing the capacity of the dryer section and the air will receive heat from the dryer exposed to the pocket. The ends of the pockets at the ends of the dryers are preferably closed to limit the free escape of air.

The felt F for example, may be termed a web support means which extends at the opposite side of the Web path from the felt F at the span of the web path 7 between dryers 14 and 17 and is offset from the felt F with respect to the direction along the web path, but overlaps with the felt F at the region of the web path between guide roll 19 for felt F and guide roll 23 for felt F2.

Thus I have provided an improved structure for a dryer section of a paper machine which meets the objectives and advantages above set forth. The web is under positive control at all times, and stray unwanted air currents are prevented from hitting portions of the web. Further, since the Web path is completely defined,

a threading path is defined which may be employed for threading the full Width of the web through the dryer section.

The drawings and specification present a detailed disclosure of the preferred embodiments of the invention, and it is to be understood that the invention is not limited to the specific forms disclosed, but covers all modifications, changes and alternative constructions and methods falling within the scope of the principles taught by the invention.

I claim as my invention:

1. In a paper machine dryer section,

a first upper horizontal tier of parallel substantially axially coplanar dryer drums,

a second lower horizontal tier of parallel substantially axially coplanar dryer drums,

said tiers arranged to carry a moving web in a path over the upper surface of the upper tier of drums and over the lower surface of the lower tier of drums with the web alternating between the upper and lower tiers in a serpentine path and so that the web path extends in spans between the upper and lower drums, a felt extending over normally web covered regions of one tier .of drums and adapted for holding the web to the drums,

and guide means for the felt between the tiers guiding the felt in spans on both sides of an individual drum in a path parallel to the spans of the web path extending to and leaving said individual drum with the felt conforming to the web path continuously over at least one half of said spans of said web path between the upper and lower tiers and so that the felt is adapted to be placed in supporting surface engagement with one surface of the web continuously over at least one half of the span of the web path extending to said individual drum, over the web pathabout said individual drum and over at least one half of the span of the web path leaving said individual drum.

2. In a paper machine dryer section,

a first upper horizontal tier of parallel substantially axially coplanar dryer drums,

a second lower horizontal tier of parallel substantially axially coplanar dryer drums,

said tiers arranged to carry a moving web in a path over the upper surface of the upper tier of drums and over the lower surface of the lower tier of drums with the web alternating between the upper and lower tiers in a serpentine path and so that the web path extends in spans between the upper and lower drums,

a felt extending over normally web covered regions of one tier of drums and adapted for holding the Web to the drums,

guide means for the felt between the tiers guiding the felt in spans on both sides of an individual drum in a path parallel to the spans of the web path extending to and leaving said individual drum and so that the felt is adapted to be placed in supporting surface engagement with one surface of the web and so that the felt is adapted to remain in engagement with the web at said spans of the web path,

and means for directing a stream of pressurized air in the direction across the web path and toward each of the felt spans in a region substantially opposite the entire felt span and adapted for holding the web to the felt.

3. 'In a paper machine dryer section,

a first upper horizontal tier of parallel substantially axially coplanar dryer drums,

a second lower horizontal tier of parallel substantially axially coplanar dryer drums,

said tiers arranged to carry a moving web in a path over the upper surface of the upper tier of drums and over the lower surface of the lower tier of drums with the web alternating between the upper and lower. tiers in a serpentine path and so that the web path extends in spans between the upper and lower drums,

a felt extending over normally web covered regions of one tier of drums and adapted for holding the web to the drums,

guide means for the felt between the tiers guiding the felt in spans on both sides of an individual 'drum in a path parallel to the spans of the web path extending to and leaving said individual drum and so that the felt is adapted to be placed in supporting surface engagement with one surface of the web and so that the felt is adapted to remain in engagement with the web at said spans of the web path,

further web support means extending along the Web path at each of said spans of the web path and at the opposite side of the web path from said felt spans and offset from but overlapping said felt spans so that said further web support means is adapted to support portions of the web at said spans of said web path not backed by said felt, means for directing a stream and toward each of the felt spans in a region substantially opposite the entire felt span and adapted for holding the web to the felt, and means for directing streams of pressurized air in the direction across the web path and toward said further web support means in regions substantially opposite the entire portions of said further web support means not overlapping said felt spans and adapted for holding the web to such portions of said further web support means.

4. In a paper machine dryer section,

a first upper horizontal tier of parallel substantially axially coplanar dryer drums, v

a second lower horizontal tier of parallel substantially axially coplanar dryer drums,

said tiers arranged to carry a moving web in a path over the upper surface of the upper tier of drums and over the lower surface of the lower tier of drums with the web alternating between the upper and lower tiers in a serpentine path and so that the web is adapted for extending in spans between the upper and lower drums,

a first upper felt extending over normally web covered regions of the upper tier of drums and adapted for holding the web to the drums,

a second felt extending over normally web covered regions of the lower tier of drums and adapted for bolding the web to the drums,

guide means between the tiers guiding the first felt parallel to the web path in the, spans and so that said first felt is adapted to be placed in surface engagement with one surface thereof,

and second guide means guiding the second feltin said spans so that said second felt is adapted to be placed in parallel surface engagement with the web spans on the opposite surface of the first felt and guiding the second felt at least to the first felt in said spans.

5. In a paper machine dryer section,

a first upper horizontal tier of parallel substantially axially coplanar dryer drums,

a second lower horizontal tier of parallel substantially axially coplanar dryer drums,

said tiers arranged to carry a moving web in a path over the upper surface of the upper tier of drums and over the lower sunface of the lower tier of drums with the web alternating between the upper and lower tiers in a serpentine path and so that the web is adapted for extending in spans between the upper and lower drums,

a first upper felt extending over norm-ally web covered regions of the upper tier of drums and adapted for holding the web to the drums,

a second felt extending over normally web covered regions of the lower tier of drums and adapted for holding the web to the drums,

guide means between the tiers guiding the first felt parallel to the web pat-h in the spans and so that said first felt is adapted to be placed in surface engagement with one surface thereof,

second guide means guiding the second felt in said spans so that said second felt is adapted to be placed in parallel surface engagement with the surface of the web opposite said 'first felts,

said guide means for the first felt guiding the felt down between spans of the web path with a felt portion extending across between felt spans and defining an air pocket between the felt portion and a lower dryer drum and adjacent spans of the web path,

and means for directing a flow of air into said pocket and adapted for holding the web spans against said second felt.

6. In a paper machine dryer section,

first upper horizontal parallel substantially axially coplanar dryer drums mounted in an upper tier,

, second lower horizontal parallel substantially axially coplanar dryer drums mounted in a lower tier,

a single dryer drum in said lower tier between first and second pluralities of dryer drums in the lower tier, said tiers arranged to carry a moving web in a path over the upper surfaces of theupper drums and over the lower surfaces of the lower drums alternating between the upper and lower tiers in a serpentine path with the web path extending in spans between the upper and lower drums,

a first felt urged against the normally web covered regions of the first plurality of the dryer drums in the lower tier,

then directed in a parallel web surface engaging path adapted for supporting a web span leading to said single drum,

then directed in a first felt run in spaced close running relationship to said single dryer drum away from said lower tier,

and a second felt directed on a second felt run in close running parallel relationship to said first run toward said single dryer drum and guided over said single dryer drum and adapted to be urged against the outer surface of the web on the single drum and thereafter guided over said second plurality of dryer drums.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS 5/ 19 60 France. 5/ 1953 Germ-any.

WILLIAM F. OlDEA, Primary Examiner.

GEORGE D. MITCHELL, Examiner.

J. SOFER, JOHN J. CAMBY, Assistant Examiners. 

1. IN A PAPER MACHINE DRYER SECTION, A FIRST UPPER HORIZONTAL TIER OF PARALLEL SUBSTANTIALLY AXIALLY COPLANAR DRYER DRUMS, A SECOND LOWER HORIZONTAL TIER OF PARALLEL SUBSTANTIALLY AXIALLY COPLANAR DRYER DRUMS, SAID TIERS ARRANGED TO CARRY A MOVING WEB IN A PATH OVER THE UPPER SURFACE OF THE UPPER TIER OF DRUMS AND OVER THE LOWER SURFACE OF THE LOWER TIERS OF DRUMS WITH THE WEB ALTERNATING BETWEEN THE UPPER AND LOWER TIERS IN A SERPENTINE PATH AND SO THAT THE WEB PATH EXTENDS IN SPANS BETWEEN THE UPPER AND LOWER DRUMS, A FELT EXTENDING OVER NORMALLY WEB COVERED REGIONS OF ONE TIER OF DRUMS AND ADAPTED FOR HOLDING THE WEB TO THE DRUMS, AND GUIDE MEANS FOR THE FELT BETWEEN THE TIERS GUIDEING THE FELT IN SPANS ON BOTH SIBES OF AN INDIVIDUAL DRUM IN A PATH PARALLEL TO THE SPANS OF THE WEB PATH EXTENDING TO AND LEAVING SAID INDIVIDUAL DRUM WITH THE FELT CONFORMING TO THE WEB PATH CONTINUOUSLY OVER AT LEAST ONE HALF OF SAID SPANS OF SAID WEB PATH BETWEEN THE UPPER AND LOWER TIERS AND SO THAT THE FELT IS ADAPTED TO BE PLACED IN SUPPORTING SURFACE ENGAGEMENT WITH ONE SURFACE OF THE WEB CONTINUOUSLY OVER AT LEAST ONE HALF OF THE SPAN OF THE WEB PATH EXTENDING TO SAID INDIVIDUAL DRUM, OVER THE WEB PATH ABOUT SAID INDIVIDUAL DRUM AND OVER AT LEAST ONE HALF OF THE SPAN OF THE WEB PATH LEAVING SAID INDIVIDUAL DRUM. 